Even less, actually. The PEP doesn't make a very clear distinction between invalid Python syntax vs. invalid type annotation, so I wanted to check if we're on the same page here: the newly valid syntax will be subject to PEP 387. We clearly are on the same page, and I don't think you need to update the PEP.
Ok, fair enough.
When I asked my curious question, I thought I misread a piece of text, not that it's a detail that went unnoticed, and could delay the PEP. I can't speak for the whole SC, but on the Monday meeting I'll suggest accepting the PEP with a note that - index assignment is also affected, and - the details around multiple unpackings in a type expression aren't specified precisely. This gives individual type checkers some leeway, but can be tightened in future PEPs.
Cool. Thanks, Petr!